To elaborate further, there is a DC-blocking capacitor in the signal
path. If you did not put the 10K to ground on the output side of the
DC-blocking cap, then there would be no way to draw any DC current
from the output. This would be a problem for some amplifiers which
need to draw a tiny input bias current (nanoamps or less). Without the
resistor, this would eventually charge up the capacitor to the full
rail voltage, or close to it, and then the circuit would clip and
distort the audio.
Sean
On Wed, Jul 20, 2011 at 1:26 PM, Herbert Graf <spam_OUThkgrafTakeThisOuT
gmail.com> wrote:
{Quote hidden}> On Wed, 2011-07-20 at 13:07 -0400, V G wrote:
>> On this page
http://www.colomar.com/Shavano/intro_opamp2.html the guy talks
>> about a ground reference resistor (10k), attached to the output of the
>> opamp.
>>
>> Why is it needed? What is he talking about when he says "ground reference"?
>> Isn't the opamp signal relative to ground anyway?
>
> The explanation in the text seems pretty clear to me:
>
> "This is to provide a ground reference for the next active device that
> this circuit is plugged into."
>
> TTYL
>
>
